Recently, in a manufacturing process of semiconductor devices, for example, an increase in diameter and decrease in thickness of semiconductor substrates, such as silicon wafers, compound semiconductor wafers or the like, are in progress. A plurality of electric circuits is formed on a semiconductor substrate, which will be hereinafter referred to as a substrate to be processed. When transferring or polishing a large and thin substrate to be processed, it is likely that the substrate to be processed is bent or broken. For this reason, a substrate to be processed is reinforced by bonding a support substrate thereto, the reinforced substrate to be processed is transferred or polished, and then the support substrate is peeled off from the substrate to be processed.
Between the substrate to be processed and the support substrate which are bonded together, an adhesive for bonding the substrate to be processed and the support substrate, a peeling agent for smoothly peeling the substrate to be processed and the support substrate, and a protectant for protecting electric circuits formed in the substrate to be processed are stacked, for example.
A peeling system that performs peeling of the substrate to be processed and the support substrate may include a peeling device for peeling the substrate to be processed and the support substrate and a cleaning device for cleaning a bonding surface of the substrate to be processed which is peeled by the peeling device. In the cleaning device, the substrate to be processed is supported and rotated by a substrate support part while a solvent of the adhesive is supplied onto the substrate to be processed, whereby the bonding surface of the substrate to be processed is cleaned.
In this regard, the protectant, the peeling agent, and the adhesive are stacked between the aforementioned substrate to be processed and the support substrate, in this order from the side of the substrate to be processed. Throughout an investigation made by the inventors, it was confirmed that the aforementioned substrate to be processed and support substrate are peeled off at an interface between the peeling agent and the adhesive. As a result, the protectant and the peeling agent remain on the substrate to be processed which has been peeled, and are then removed when the substrate to be processed is cleaned.
However, although the aforementioned peeling system peels off the substrate to be processed and the support substrate which are bonded by the adhesive, it does not consider that, in addition to the adhesive, the protectant and the peeling agent are stacked between the substrate to be processed and the support substrate. That is to say, in the cleaning device of the aforementioned peeling system, the adhesive on the substrate to be processed is removed by supplying the solvent of the adhesive on the substrate to be processed. However, since removing the protectant and the peeling agent is not considered as described above, in some cases, the aforementioned peeling system cannot properly clean the bonding surface of the substrate to be processed. Further, if the protectant and the adhesive are different materials, for example, it takes a long time to remove the protectant and the adhesive using the aforementioned peeling system.